How many inches does your hair need minimum to tie in a ponytail...?

so i always had a buzz cut my whole life basically and i really wanted to grow my hair long always wanted a ponytail lol, my hair is somewhat nappy but more curly i am from carribian origin from trinidad my parents are east indian and African, so that can sort decribe my hair texture, but i have like about half an inch of hair right now and was wondering how long would i have to wait for it to be long enoughs to ponytail even if it is just barely. i am also using the Mira hair oil i got from online if any of your had any experience with that it claims to grow your hair alot faster does anyone know if it is true i just started using it about 2 weeks ago so i think its is to soon to tell and other tips would be greatly appreciated